1. Field of the Invention
The present invention relates to an active matrix display apparatus having a COG (Chip-On-Glass) terminal portion to which a separate semiconductor integrated circuit is directly connected in a peripheral portion, and a method of manufacturing the same.
2. Description of Related Art
Conventionally, as display apparatuses such as liquid crystal panels, active matrix display apparatus in which a thin film transistor for display control is disposed in each pixel have been widely used.
In such display apparatuses, an external data signal (video signal) or the like is received within a panel and is then supplied to each pixel. In order to achieve this, data lines are provided in the vertical direction and selection (gate) lines are provided in the horizontal direction, and, with a data signal being supplied to a data line, an associated pixel is selected by the corresponding gate line, thereby controlling supply of the data signal to each pixel. Thus, this structure requires control of data supply to the data line and selection of the gate line, which therefore requires a vertical driver and a horizontal driver in these display apparatuses.
These vertical and horizontal drivers are often provided within the display panel. Here, comparatively high speed processing is required for the horizontal driver, which must control the operation of supplying a data signal to a data line in each column within one horizontal period. Accordingly, in many cases, the horizontal driver is provided within a separate semiconductor integrated circuit (a horizontal driver IC) from which a data signal is supplied directly to each data line. In this case, it is preferable to adopt a COG (Chip On Glass) structure in which each data line is extended to the peripheral portion of the panel where a terminal of the horizontal driver IC is connected via an ACF (anisotropic conductive film)
An example structure which adopts the above-described COG structure is shown in FIG. 18. A connection portion 10 connected to a data line DL is covered with a protective film 12 which is an insulating film. A portion of this protective film 12 is then removed to form a contact hole, and a transparent conductive film 14 including this contact hole is formed. Consequently, the transparent conductive film 14 contacts the connection portion 10 in the portion where the protective film is removed. Further, a portion of the transparent conductive film 14 located above the protective film 12 is used as a terminal portion of the COG structure. Here, the terminal portion of the COG structure is formed on a TFT substrate 16 on which a thin film transistor (TFT) of each pixel as described above is formed.
Here, the protective film 12 is a planarization film which covers the thin film transistor provided in each pixel. Further, in each pixel, a transparent conductor, such as a pixel electrode formed of IZO, for example, is formed on the planarization film. Therefore, the transparent conductive film 14 is formed in the same process as a process in which the pixel electrode is formed.
As described above, the planarization film and the transparent conductive film 14 which are formed in the pixel area can be used for forming the terminal portion of the COG structure without performing any additional process. Further, use of the transparent conductive film in the terminal portion is disclosed in Japanese Patent Laid-Open Publication No. Hei 06-180460, for example.
The above structure, however, suffers from a problem that sufficient connection cannot be achieved by application of pressure onto the ACF in the terminal portion described above because the planarization film is relatively soft.